A port is a "virtual channel" used to transfer packets of a specific protocol between a client and a server. Each port has a number assigned to it to perform a particular service(eg: telnet is generally number 23). services are programs (like http service, smtp service, ftp service,etc) running on that server that can be connected to. suppose you scan a particular machine in the network and found that port 23 is open that means you can access that machine using telnet (since port 23 refers to telnet).

There are different forms of hacking, even if you see the source code of a website without doing any manipulation than also it is a type of hacking.

Meh. If a site has been *defaced* you'll know.. there's usually some cocky comment with an email address and a skiddie alias. You could also check FTP login times. If you're the only webmaster, and there's a login at a time you KNOW you weren't online, you've probably had someone inside the account.

if you want to check out hacking for yourself(in a legal manner) go to www.hackthissite.com. its sweet. i know of several sites that have been hacked. one of my forums(paintball forum) was hacked a while back. somebody else mentioned another site that got minorly hacked(micheif mostly) whoever it was just went it and reprogramed the html to redirect to a site sayin it was defaced or some such bs.